sin(θ+105)cos(θ-15)-cos(θ+105)sin(θ-15)_数学解答

sin(θ+105)cos(θ-15)-cos(θ+105)sin(θ-15)

人气：289 ℃　时间：2020-10-02 03:10:02

解答

sin（a-b）=sinacosb-cosasinb
代入后θ就会消掉
为根号3/2sin(a-b)=sinacosb-cosasinb?我们只教了cos(a-b)=sinasinb+coacosb